MDF MANUAL

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1. Introduction............................................................................................................... 1.1. MDF with all its possibilities..... ..................................................................................................................... 1.2. Spanolux ...................................................................................................................................................... 1.3. Wood Based Solutions .................................................................................................................................

2. What is MDF?........................................................................................................... 2.1. General: what is MDF .................................................................................................................................. 2.2. Spanolux production process....................................................................................................................... 2.3. MDF product classes...................................................................................................................................

3. Technical characteristics......................................................................................... 3.1. Weight by volume and density profile........................................................................................................... 3.2. Surface degree of finish............................................................................................................................... 3.3. Sand content................................................................................................................................................ 3.4. Dimensions.................................................................................................................................................. 3.5. Bending strength and modulus of elasticity................................................................................................. 3.6. Tensile strength perpendicular to surface.................................................................................................... 3.7. Screw pull-out resistance............................................................................................................................. 3.8. Formaldehyde emission.... .......................................................................................................................... 3.9. Thickness swelling 24 hours......................................................................................................................... 3.10. Durability......... ........................................................................................................................................... 3.11. Surface strength.... ..................................................................................................................................... 3.12. Fire behaviour............................................................................................................................................. 3.13. Building physical properties.... ................................................................................................................... 4. General guidelines for the use of MDF.................................................................... 4.1. Transport and storage ................................................................................................................................. 4.3. Moisture content in MDF .............................................................................................................................

5. Machining ............................................................................................................... 5.1. Sawing ......................................................................................................................................................... 5.2. Drilling.......................................................................................................................................................... 5.3. Profiling (milling) .......................................................................................................................................... 5.4. Laser cutting ............................................................................................................................................... 5.5. Sanding .......................................................................................................................................................

6. Fasteners and joints ............................................................................................... 6.1. Screws ......................................................................................................................................................... 6.2. Nails ............................................................................................................................................................ 6.3. Rivets .......................................................................................................................................................... 6.4. Glues ........................................................................................................................................................... 6.5. Joints ..........................................................................................................................................................

7. Surface finish .......................................................................................................... 7.1. Painting ........................................................................................................................................................ 7.2. Powdercoating ............................................................................................................................................ 7.3. Veneer ......................................................................................................................................................... 7.4. Melamine ..................................................................................................................................................... 7.5. Finishing with paper or plastic foil ................................................................................................................ 7.6. Transfer foil .................................................................................................................................................. 7.7. HPL (= High Pressure Laminate) ................................................................................................................. 7.8. Membrane pressing .................................................................................................................................... 7.9. Edge finish ................................................................................................................................................... 7.10. Special: MDF Design ..................................................................................................................................

8. Applications and references with MDF ................................................................. 8.1. Interior ......................................................................................................................................................... 8.2. Furniture ...................................................................................................................................................... 8.3. MDF on the construction site ...................................................................................................................... 8.4. Overview: Which type of Spanolux MDF to use for which application? .......................................................

9. Environmental and quality labels, certification ...................................................... 9.1. CE marking ................................................................................................................................................. 9.2. PEFC ........................................................................................................................................................... 9.3. FSC ............................................................................................................................................................. 9.4. Der Blaue Engel .......................................................................................................................................... 9.5. Ministerial Approval ..................................................................................................................................... 10. Spanolux MDF product range ...............................................................................

11. Relevant standards ................................................................................................

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1. Introduction

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1.1. MDF with all its possibilities

MDF (Medium Density Fibreboard) is the preferred wood panel material of wood processors. Spanolux produces a variety of MDF types, each of which provides an ideal solution for a wide range of possible applications. The processor of MDF board material may be an industrial furniture maker, an interior builder, a carpenter... or a private DIYer. The numerous application, processing and finishing possibilities (brought about by constant innovation and technological progress) have given rise to many questions regarding MDF and its proper use: the different properties of the different MDF types, special lacquer finishes, processing of lightweight MDF, etc.

The purpose of this Spanolux MDF Manual is to provide the customer with a reference guide on the use and processing of Spanolux MDF. Taking into account the specific properties of MDF board material, this manual develops user guidelines to deal with some of the frequently encountered problems.

All information contained in this MDF manual is not to be used for legal proceedings.

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1.3. Wood Based Solutions

Spanogroups core competence is woodworking and wood transformation, using wood in all its forms for the production of board material, energy or composites.

Spanogroup continuously builds on its know-how of transforming wood to develop new innovative products in order to diversify its product portfolio and optimise the use of wood resources.

With its MDF boards, Spanolux provides a solution for every use or application via its Wood Based Solutions such as: Water Resistant, Fire Retardant, Construction/ Flooring, Health & Environment, Light Products and Interior Design.

Figure 2: Spanogroup schematic diagram

1.2. Spanolux

Spanogroup

Spanogroup consists of four companies: Spanolux, Spano, Dekaply, and Balterio. Spanolux, located in Vielsalm, produces basic MDF. Balterio, located on the same site, produces HDF-based laminate flooring. Spano, located in Oostrozebeke, is active in the production of particleboard. Finally, Erembodegem-based Dekaply specialises in the melamine facing of particleboard and MDF, and in the manufacture of furniture components.

Spanolux

Spanolux, possibly the best MDF producer in the world, has developed a market-driven, customer-oriented strategy. Its corporate philosophy is to offer customers the products they want, in all qualities and quantities. All of Spanolux products can, upon request, be delivered with the FSC and PEFC certificates.

1.3.1. Moisture Resistant: Unafraid of high humidity

Problem description

Wood does not like moisture. Not only direct contact with water but also high humidity is dangerous for wood and for MDF boards in particular. A damp environment, with a relative humidity exceeding 70%, may be present in any house, e.g. in the bathroom, the kitchen or under the roof.

Wood may also be exposed to high humidity during the construction phase. This may be due to adverse weather conditions, but also after plastering the walls or pouring the floors the relative humidity inside a building can reach 90% or higher.

Moisture causes wood to change (linear expansion, swelling) and in the case of MDF board material it may have a highly adverse impact on its technical characteristics (such as rigidity, bending strength). In the most critical of environments, even surface fungus may occur.

Solution

Spanogroup, and Spanolux in particular, offers solutions that allow MDF boards to be used in a damp environment. The board materials are in fact produced using a moisture resistant glue that is based on non-hydrolisable and also moisture repellent glue bonds. The glues used are so-called MUF (Melamine Ureum Formaldehyde) glues and feature an efficient curing system. This special Spanolux production process positions the finished product far above the common standard values. These boards can be applied in service class 2 environments (not in outdoor applications) and are capable of withstanding accidental contact with water. The products are characterised by low swelling and limited linear expansion when exposed to an increased humidity level. Brief exposure to water (e.g., rain shower at a site) will not substantially alter the mechanical characteristics. Spanolux moisture-resistant MDF boards (Umidax, Umidax Noir and Umidax Light) can be melaminated, laminated or coated with another surface finish without any problem. Sawing and milling is possible using standard tools.

Figure 1: Spanolux and Balterio Vielsalm

Wood sources: fresh wood waste wood

recycling wood

Corecompetence:

WOOD TRANS-FORMATION

Traditional businesses

New projects

Particleboard MDF board

Bio-mass Energy plant

Wood composites

Melamine faced board

Laminate flooring

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1.3.2. Fire Retardant: Fire: every second counts!

Problem description

Sadly, not a day goes by without a fire breaking out somewhere. Nobody can predict the danger, a fire is usually caused by accident or negligence. However, we can and must try to keep the fire from spreading. In a fire, every second counts for the slower the fire spreads, the more time the emergency services have to limit personal injury and property damage.

Breakout of fire

A fire breaks out if the following elements are present to a sufficient degree:

Heat source: a spark caused by a short-circuit, an overheated machine, a smouldering cigarette, etc.

Oxygen Combustible material such as furniture, clothes,

books, etc.

If one of these elements is missing, there is no risk of fire. Of these three elements, however, there are two that cannot be kept under control: the heat source (which is usually created by accident) and oxygen (which is always present to a sufficient extent in air), so that all attention should be directed towards the last element: the combustible material. Fire safety can be considerably increased through the use of non-combustible or fire retardant material.

Spread of fire

Once a fire has broken out, it can spread in different ways:

By conduction: The heat is transferred from one material to the next. The heat conduction of the material plays an important role in this process. Thus, a metal, while non-combustible, will transfer heat faster than wood.

By convection: Hot air and combustion gases rise up and heat other material that will in turn catch fire.

Fire behaviour of materials

It is important to know how construction materials will behave in the event of a fire. Do they easily catch fire? Do they help spread the fire? Do they cause high amounts of smoke or gas? But there are also other questions to be answered. How, for instance, will the material itself react to high temperatures? Will it deform, bend (e.g. steel), crack (e.g. plaster) or melt (e.g. plastic)? Wood products are known to react favourably to fire and therefore score well on the above-mentioned criteria.

Flame spread

Flame spread is the rate at which flames travel along the surface of a given material. This rate varies from one material to another. The degree of flame spread can be subdivided into four classes:

Class 1 (M1) - No flame spread Class 2 (M2) - Slight flame spread Class 3 (M3) - Average flame spread Class 4 (M4) - High flame spread

Flashover and combustibility

The spread of fire is determined not only by the flame spread but also by the heating of non-combustible materials. This may result in the generation of ignitable gases, which will in turn cause other materials to catch fire (flashover).

Depending on their contribution to flashover, these materials are subdivided into four classes:

Class 1 - No contribution to flashover Class 2 - Limited contribution to flashover Class 3 - Average contribution to flashover Class 4 - Large contribution to flashover

Solution

The development of fire retarding products has been a priority within Spanogroup for more than 30 years, which has resulted in an extensive know-how in the field of fire behaviour of wooden board material. Spanogroup, and Spanolux in particular, offers solutions for flame spread, flashover, smoke development and burnthrough time. Spanolux fire retardant MDF boards are CE marked and regularly tested and inspected by national and international agencies. Certificates and test reports are available upon request. Sister company Dekaply specialises in the melamine facing of fire retardant MDF boards: Firax, Firax Class 0 and Firax Light.

1.3.3. Interior Decoration: From panel to beauty

Problem description

Domestic interiors change and homes are increasingly designed to meet the needs and requirements of modern man. Children each have their own room and the kitchen emerges as the central living space in many homes.

In todays society, the home is becoming not only a place for relaxing but also a showcase for modern technology. Domotics or home automation pervades all parts of the home, from the bedroom through the living room to the kitchen.

Design, too, is increasingly gaining acceptance and recognition. Beauty is added to functionality. New residential concepts are emerging in the form of lofts, apartments or modern, open-plan villas. Just like fashion and culture, the appearance of homes is becoming more sensitive to changes and trends.

Solution

Everyone has their own preferences when it comes to shapes, colours and finishes. Dekaply specialises in the melamine coating of all types of MDF with a wide range of uni-colours and trendy wood decors. This also enables it to respond swiftly and efficiently to new market trends:

Accessory products such as matching laminates, edge band melamine and ABS are kept in stock.

Flexible dimensions and choice of carrier board. Specialised in melaminated fire retardant boards,

including Firax, Firax Class 0 and Firax Light. Also MDF Prime, coverd with a white primer is ready to paint and ideal for interior applications. Umidax Noir, colored black in the mass, gives the possibility for creative applications in modern interior decoration.

CONSTRUCTION&FLOORING

1.3.4. Construction / Flooring: Natural construction materials

Problem description

The construction of houses, apartments, lofts, office and public buildings is undergoing a tremendous change as increasingly innovative products are being developed for use as building materials. Also the use of wood and wood board material continues to evolve within the construction sector, both in load bearing and non-load bearing applications.

Solution

Spanogroup produces CE marked products for the building sector, e.g. the MDF Standard.

Moisture resistant boards are used for applications in high humidity environments. They guarantee limited swelling and minimise linear expansion due to humidity variations. The Umidax type can be used for this purpose.

For applications where specific fire safety requirements apply, the Spanolux MDF boards can be used. These MDF boards comply with rigorous fire standards and carry various international certificates. The Firax and Firax Class 0 MDF types can be used for this purpose.

For applications where air quality is critical, Spanolux has developed MDF boards with a formaldehyde emission that is equal to or less than that of natural wood. The MDF type to be used for this purpose is Pure.

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1.3.5. Health & Environment: For a clean world

Problem description

The Kyoto protocol has placed the CO2 issue high on the agenda. In the combustion process, hydrocarbons are converted into CO2, which as greenhouse gas is responsible for global heating. Switching from fossil fuels to biofuels does not reduce but can compensate for the amount of greenhouse gases through the cultivation of crops. Wood and forests are strong CO2 sinks. If wood is not burned and thus given a long life cycle, the greenhouse gas is fixed over this long period. Wood and wood products therefore constitute an important step in the control of greenhouse gases.

Public awareness of nature, environment and energy is a trend in society that can no longer be denied and one that will continue to command a great deal of attention in the future. In housing construction, too, there is a growing trend towards the use of ecologically sound techniques. The choice for environmentally friendly products and products that are not harmful to human health results in properly insulated and ventilated houses with good air quality.

Solution

Spanolux offers MDF boards with low formaldehyde content. Our standard products invariably meet the rigid E1 standard for formaldehyde emission, but our low-formaldehyde MDF boards contain an amount of formaldehyde that is equal to or less than that of natural wood. The Spanolux MDF types to be used for this purpose are Pure and Pure Light.

Also in terms of production technology, the Spanolux production departments are equipped with environmental- technical facilities to ensure compliance with European environmental standards.

1.3.6. Light Products: Innovative by weight

Problem description

Product development is growing exponentially: electronics, domotics, new materials, etc. This also applies to board material. A major impulse for change is the demand for lighter material. Light material offers a number of significant advantages:

The lighter materials are made, the fewer raw materials are required. The future of the world depends to a significant degree upon the judicious use of the available raw materials.

Furthermore, light board material offers distinct ergonomic benefits. The handling and processing of heavy material calls for appropriate tools and imposes a heavy physical load on the user. Transportation costs, too, are to a great extent determined by the weight of the product.

Finally, there is the constant search for innovative products, products with new characteristics that open up new fields of application.

Solution

The creation of light board materials is one the top priorities of Spanoluxs development programme, the aim being to provide light MDF boards that can be perfectly processed for their respective applications.

Thanks to its sustained research and development efforts, Spanolux can already today propose a light product for most MDF board materials, notably Fibrabel (600 kg/m), MDF Ultra Light (500 kg/m), MXL (400 kg/m) in the standard product range, and Umidax Light, Firax Light and Pure Light in the moisture-resistant, fire-retardant and low-formaldehyde lines respectively.

2. What is MDF?

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2.1. General: what is MDF?

MDF (Medium Density Fibreboard) was developed in the United States and has since 1973 been produced in Europe, where it achieved an effective breakthrough only in the 1990s. MDF is manufactured using the so-called dry process in which the wood fibres are mixed with glue and pressed in dry condition.

Initially, the furniture industry processed MDF as an alternative to solid wood panels. Subsequently, MDF was also used for other furniture parts. Finally, applications in interior design and construction were identified. By the end of 2004, Europes total production capacity was approximately 11.9 million m per year.

2.2. Spanolux production process

The Spanolux MDF production process is illustrated step by step from raw material to finished product, in Figure 3. Raw materials:

For its MDF production, Spanolux uses spruce (Picea Abies) as base raw material (1), in the form of round or sawn timber, originating from nearby saw mills.

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Manufacture of chips:

After debarking, the round timber is reduced to small chips (2) approx. 20 mm in length. Both in-house produced and external chips are stored in silos, after which they are screened and washed. Chips larger than 40 mm or smaller than 5 mm are removed from the process flow. The other chips are washed (3) in order to eliminate possible contaminants such as minerals or metals.

Manufacture of fibres:

The rinsed chips are steamed under pressure for a few minutes at a temperature of approx. 160C. After softening, the chips are fiberised in a defibrator using two structured grinding discs: one stationary and one rapidly rotating disc. A wood-fired energy plant (4) provides steam together with hot air and thermal oil for downstream processes.

Addition of resin mixture and drying:

The loose fibres and/or wood bundles are glued in a so-called blowline, i.e. a pipe through which the fibres are blown at high speed. The glue resin used is urea-formaldehyde (UF) resin, or melamine-urea-formaldehyde (MUF) resin for boards with increased moisture resistance.

Figure 3: Spanolux production process

In addition, other additives can be added together with the resin, e.g. to improve the fire retardant properties of the board. Next, the fibres are dried (5) and stored in a small buffer silo for the Pendistor or spreading machine. The wet, resinated fibres are dried in two steps, resulting in virtually dry fibres being spread and pressed.

Formation of the mat:

In the forming station, the dried fibres are spread onto a belt, with the air at the bottom being sucked off, thereby causing the fibres to form a so-called pulp or mat. (6). The mat of spread fibres is almost 30 times as thick as the board at the end of the production line.

Pressing of the board:

Pressing of the MDF boards is accomplished in two steps. First the pulp is passed through a belt press, which reduces the thickness and imparts a certain stability to the mat. Then the edges are trimmed and the mat is fed into the continuous main press. The continuous press consists of two steel belts that move on a chain system through the press. In this step, the boards are pressed at high temperature and pressure. At the end of the press the boards are sawn to length. In principle, it is possible to produce

an infinitely long board, but in practice the length of the MDF board is limited by the stacking capabilities and the subsequent process steps (sanding and sawing). Capabilities of the Spanolux continuous press: widths from 2450 to 2550 mm lengths from 3660 to 6310 mm thicknesses from 6 to 38 mm Final operations:

When the boards exit from the press and have initially been sawn to length, they are cooled with ambient air in a star dryer or cooling carousel. Next, the boards are temporarily stored in a conditioned room to ensure complete stabilisation of the board. After conditioning, the boards are sanded (7) on a 4-head sander. In this process, the board is calibrated and sanded with e.g. 60, 80, 100 and 150 grit. Before the boards are stored (9) for subsequent shipment, they are trimmed to size (8) and carefully packed.

Figure 4: Spanolux dryer

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2.3. MDF product classes

MDF is produced in various types and qualities. In terms of weight by volume, MDF can be classified as follows: HDF: 800 kg/m MDF: 650-800 kg/m Light MDF: 550-650 kg/m Ultralight MDF 450-550 kg/m

European standard NEN-EN 622-5 further subdivides MDF into various application classes by the addition of one or more letters:

H: increased moisture resistance E: outdoor applications L: structural applications A: permanent loads S: momentary (short-term) loads FR: fire retardant applications (not included in the

standard)

Based on this classification, the following specific MDF types can be defined:

MDF-LA: Structural applications in dry environments (all load classes cf. EN 1995-1-1)

MembranePureMDF Standard

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Table 1: MDF product classes / Spanolux MDF

Spanolux MDF

Wood Based Solutions

MDF-LA Membrane v

Pure v v

MDF Standard v v

FR-MDF-LA Firax Class 0 v v

Firax v v

MDF-HLS Umidax v v

Umidax Noir v v

L-MDF Fibrabel v v

Pure Light v v

L-MDF-FR Firax Light v v

L-MDF-HLS Umidax Light v v

UL2-MDF MDF Ultra Light v v

MXL v v

CONSTRUCTION&FLOORING

The specific properties of MDF are determined by the production method, the quality of the raw materials, and the resin recipe. Spanolux achieves a constant quality of the various product types through advanced process and product control. The quality lab uses an extensive test protocol under which each production batch is tested for a number of major quality parameters.

3.1. Weight by volume and density profile

The weight by volume represents the mass per unit of volume. For MDF boards, the weight by volume varies from 450 to 800 kg/m. Spanolux even produces MXL with a weight by volume of approx. 400 kg/m. The Spanolux MDF with the highest density is MDF Membrane, which has a weight by volume of over 800 kg/m.

In the case of MDF boards, the weight by volume is not constant across the thickness and across the width (and to a lesser extent across the length) of the board. The press can be set for the production of MDF with high or low densified cover layers. Light MDF is produced with high densified cover layers. MDF for laminate flooring is pressed as homogeneously as possible.

Upon delivery, the tolerance on the average weight by volume within a single board must be less than 7% (EN 323).

The weight by volume of the board is not always an indication for the properties and performance of the board. Parameters that are equally important include the variation of the weight by volume, the weight by volume of the cover layers, etc. It is important to use the appropriate MDF board with the correct weight by volume if the specified processing and application requirements are to be met.

Figure 5 shows the density profile of a Fibrabel MDF with a weight by volume of 600 kg/m. The profile shows that the surface layers, over a limited thickness with respect to the total board thickness, exhibit a density of 950 to 1000 kg/m, i.e. significantly higher than the average board density (600 kg/m). The high densified surfaces of the MDF board allow e.g. a wet paint surface finish.

By contrast, the almost horizontal line, between the peaks on the left and right, represents a virtually constant density of 500 kg/m. This homogeneous core has a slightly lower density than the average board density (600 kg/m). The homogeneous core of the MDF board allows for simple processing of the board, e.g. profile milling.

The lighter the MDF board, i.e. the lower the average density, the greater the difference between the constant lowest density in the core of the board and the highest density at the surfaces of the MDF board will be. For an MDF board with a lower average

3. Technical characteristics

Figure 5: Fibrabel density profile (measured before sanding, i.e. a thickness of 18.6 mm, which yields a thickness of 18 mm after sanding)

3.2. Surface degree of finish 3.2.1. Sanding quality

As a rule, MDF boards are sanded in production with 100 grit and then with 150 grit. This surface degree of finish is suitable for further processing of the board. Finish options such as painting, veneering, melamine facing, etc. will be discussed in detail further on this MDF manual.

Sanding with a specific or finer grit, already in the production stage, is possible upon request.

3.2.2. Surface absorption

An important parameter for obtaining a uniform finish is the surface absorption of MDF, notably the extent and rate of penetration of liquids. If the surface absorption is too high or non-uniform, stains may appear on the surface during the finishing process. In addition, differences may occur in the curing of paints, resulting in insufficient adhesion or too rapid penetration, so that the desired result will not be achieved.

The surface absorption cannot be determined visually and must be carried out using the method specified in EN 382-1. For surface absorption, the following general conclusions can be drawn:

density, the difference resides mainly in a lower constant density in the core of the board.

FR-MDF-LA: Structural applications in dry conditions, with fire retardant properties

Firax Class 0Firax

MDF-HLS: Structural applications in humid conditions (momentary or short-term loads cf. EN 1995-1-1)

Umidax

Umidax Noir

L-MDF: Light MDF, for general applications in dry conditions

Fibrabel

Pure Light

L-MDF-FR: Light MDF, for general applications in dry conditions, with fire retardant properties

Firax Light

L-MDF-H: Light MDF, for general applications in humid conditions

Umidax Light

UL2-MDF: Ultralight MDF, for general applications in dry conditions

MDF Ultra LightMXL

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Table 2: Tolerances on nominal dimensions MDF

The type Membrane has a slightly lower surface absorption than the Pure and MDF Standard types.

The lighter Fibrabel, MDF Ultra Light and MXL types have a slightly higher surface absorption than the above-mentioned types.

Because of their moisture resistant properties, the Umidax, Umidax Noir and Umidax Light types have a lower surface absorption than all of the above-mentioned MDF types.

Because of the added fire retardants, the Firax, Firax Class 0 and Firax Light types exhibit a higher surface absorption than the light MDF types.

3.3. Sand content

Contaminants (in particular sand) in wood board material adversely affect the quality and lifetime of the cutting tools. The abrasive action causes saw blades, cutter heads and other cutting tools to become dull more rapidly, resulting in a poorer finish quality of the end product. Since MDF requires a high degree of processing, it is important to ensure that the board contains as few contaminants as possible. The standard prescribes a sand content < 0.05 %. Spanolux processes only debarked and washed chips, allowing it to achieve an exceptionally low sand content in the order of 0,00x %.

3.4. Dimensions

3.4.1. Length / width / thickness

Spanolux produces boards in the following standard thicknesses and dimensions:

Thicknesses (mm): 6, 8, 9, 10, 12, 15, 16, 18, 19, 22, 25, 28, 30, 38

Standard board dimensions (mm): 1220 x 3050, 1220 x 3050, 1830 x 2440

The high capacity saw supports all sawing dimensions. In principle, all thicknesses and lengths/widths are available within the press capabilities and can be produced upon request. The Spanolux press capabilities for MDF are as follows:

Widths from 2450 to 2550 mm Lengths from 3660 to 6310 mm Thicknesses from 6 to 38 mm

For the current stock programme, please refer to Chapter 10, which contains the Spanolux product and stock range.

Table 2 below contains the general specifications for tolerances on nominal dimensions in accordance with standards EN 324-1 and 324-2.

Property Standard Unit Fibreboards - Speci-fications Part 1: Gen-

eral requirements

Nominal thickness classes (mm)

< 19 > 19

Tolerances on nominal dimensions:

Thickness EN 324-1 mm 0,2 0,3

Length and width EN 324-1 mm/m 2.0 mm/m, max. 5.0 mm

Squareness EN 324-2 mm/m < 2,0 mm/m

Straightness length and width

EN 324-2 mm/m < 1,5 mm/m

3.4.2. Dimensional stability

Wood and wood based board materials shrink and swell according to variations in the moisture content in the material. Compared with solid wood, MDF is a relatively stable material. The action, expressed as a % per % change in moisture content within the board, amounts to 0.05% in the surface of the board and 0.35% in the thickness of the board. By comparison, the action of solid wood amounts to 0.5% in tangential direction and 0.2% in radial direction. The moisture content in a wood panel mainly depends on the ambient humidity and temperature: prior to testing, test specimens are conditioned at a temperature of 20 2C and a relative humidity of 65 5%.

The dimensional stability is specified in standard EN 318.

The example here is a Fibrabel MDF door panel, 600 mm wide, 15 mm thick. With an increase in relative humidity from 35% to 85%, the moisture content in the panel can increase by approx. 5%. This causes a dimensional change of approx. 1.5 mm in the width and 0.25 mm in the thickness of the panel. The application of finish coats will slow down the effect of variations in relative humidity on the wood moisture content of the panel, and all the more so if the finish coats are more vapour tight.

After production, Spanolux MDF has a moisture content of 8 3%, in compliance with the EN standard. At the time of delivery to the end-user, however, the moisture content may have altered due to ambient factors during transport and storage. Storing the panels in a humid environment on the construction site inevitably leads to water absorption (albeit to a limited degree); conversely, the moisture content decreases in a very dry environment. Such moisture content variations initially occur at the edges of the panels and in the outer panels of a stack, but can subsequently spread to all panels of the stack.

Individual MDF panels that are exposed to free ambient air will reach an equilibrium moisture content within a couple of days. MDF panels located in the middle of a stack, by contrast, will take several weeks before they reach the equilibrium moisture content.

The ratio between the equilibrium moisture content of Standard MDF and Umidax (expressed in mass percentage) and relative humidity is shown in Figure 6.

Figure 6: Comparison of moisture content in Standard MDF and Umidax.

The moisture content of MDF is determined by measuring the loss of mass between the condition at the time of sampling and the condition after drying to constant mass at 103C (EN 322).

An alternative, but less accurate, measuring method is the use of electric hygrometers designed for solid wood. The measuring accuracy of these instruments can be improved by using a specific calibration scale for MDF, if such a scale is provided by the supplier of the instrument.

Dimensional variations can to some extent be limited by treating and processing MDF at a moisture content that approximates, as closely as possible, the expected final equilibrium moisture content. In Northern European countries, a moisture content of 8 2% is to be expected for MDF in a normal indoor climate. In Southern Europe, a lower moisture content is to be expected.

3.5. Bending Strength & Modulus of Elasticity

The bending strength determines the load limit value of an MDF board, and the modulus of elasticity the stiffness and therefore the degree of deformation at load.

Table 3 shows the average bending strength and modulus of elasticity for the various MDF types, measured in accordance with EN 310.

EN 310 is used to classify MDF, not to generate calculated values.

MDF class Spanolux products Bending strength EN 310 (N/mm)(average values)

Modulus of elastic-ity EN 310 (N/mm)

(average values)

MDF-LA Membrane - -

Pure 37 2950

MDF Standard 37 3850

FR-MDF-LA Firax Class 0 27 3200

Firax 32 3400

MDF-HLS Umidax 40 4000

Umidax Noir 40 4000

L-MDF Fibrabel 29 3050

Pure Light 27 2900

L-MDF-FR Firax Light 23 2500

L-MDF-HLS Umidax Light 30 3100

UL2-MDF MDF Ultra Light 19 2000

MXL - -

Table 3: Bending strength and modulus of elasticity for various MDF types as per EN 310.

For strength calculations as per Eurocode 5, the characteristic values are used, which are combined with correction factors kmod and kdef.

The bending strength and E-modulus of a product need to be known in order to know how they relate to loads in buildings. Table 4 indicates the minimum load values for different area types as described in Eurocode 1. Category Type of surface qk (kN/m) Qk (kN)

Floors, accessible roofs:

A General 2 2

Stairs 3 2

Balconies 4 2

B General 3 2

Stairs, balconies 4 3

C General 5 4

Areas with tables 3 4

Areas with fixed seats

4 4

Areas susceptible to large crowds

5 7

D Retail shops 5 4

Department stores

5 7

E General 5 7

Inaccessible roofs H slope < 20 0,75 1,5

slope > 40 0 1,5

Table 4: Load on floors and roofs

For area types A to D, a medium term load duration is assumed, whereas for types E and H, long term and short term, respectively, are used (see Table 4). Short term load duration is also applied for concentrated load Qk.

Table 5: Load duration classes

Load duration class Accumulated duration

Examples of loading

Permanent > 10 years Self-weight

Long-term 6 months 10 years

Storage

Medium-term 1 week 6 months Imposed load

Short-term < 1 week Snow and wind

Instantaneous Occasional load

025 40 60 80

2

4

6

8

10

12

Standard MDF Umidax

Relative humidity of air (%)

Mo

istu

re c

onte

nt

of M

DF (

%)

15

3

14

For MDF, the following correction factors apply (see Table 6).

Table 6: Comparison kmod and kdef factors of MDF for service classes 1 and 2

MDF-LA (Structural applications in dry environments) and MDF-HLS (Structural applications in humid conditions) are suitable for construction applications. The characteristic values for these MDF types are given in EN 12369-1. An overview of these values is shown in Tables 7 and 8.

The 5% characteristic values for stiffness are calculated by taking 85% of the average value of the tables. If immediate deflection has to be limited, deflection u must be less than l/300 (where l = support point distance). If the final deflection under prolonged load is taken into consideration, the following condition must be satisfied: u < l/200.

3.6. Tensile strength perpendicular to surface

The tensile strength perpendicular to surface is defined in accordance with EN 319 and determines the normal force required to pull a panel apart in the thickness direction. The tensile strength thus provides important information about the panels

Property Test method

Unit Nominal thickness range (mm)

1,8 tot 2,5 > 2,5 tot 4,0 > 4 tot 6 > 6 tot 9 > 9 tot 12 > 12 tot 19 > 19 tot 30 > 30 tot 45 > 45

Thickness swelling 24h EN 317 % 35 30 18 12 10 8 7 7 6

Tensile strength EN 319 N/mm 0,70 0,70 0,70 0,80 0,80 0,75 0,75 0,70 0,60

Bending strength EN 310 N/mm 34 34 34 34 32 30 28 21 19

Modulus of elasticity EN 310 N/mm 3000 3000 3000 3000 2800 2700 2600 2400 2200

Option 1

Thickness swelling after cyclic test

Tensile strength after cyclic test

EN 317

EN 321

EN 319 EN 321

%

N/mm

50

0,35

40

0,35

25

0,35

19

0,30

16

0,25

15

0,20

15

0,15

15

0,10

15

0,10

Option 2

Tensile strength after boiling test *

EN 319

EN 1087-1

N/mm 0,20 0,20 0,20 0,15 0,15 0,12 0,12 0,10 0,10

*) EN 1087-1: 1995 is applied with the adapted procedure according to Annex B in EN 622-5.

Property Test method

Unit Nominal thickness range (mm)

1,8 to 2,5 > 2,5 to 4,0

> 4 to 6 > 6 to 9 > 9 to 12 > 12 to 19 > 19 to 30 > 30 to 45 > 45

Thickness swelling 24h

EN 317 % 45 35 30 17 15 12 10 8 6

Treksterkte EN 319 N/mm 0,70 0,70 0,70 0,70 0,65 0,60 0,60 0,55 0,50

Buigsterkte EN 310 N/mm 29 29 29 29 27 25 23 21 19

Table 7: Characteristic values of MDF as per EN 622-5: MDF-LA

Table 8: Characteristic values of MDF as per EN 622-5: MDF-HLS

MDF class Spanolux MDF Screw withdrawal resistance (N) EN 320

(average values)

Face Edge

MDF-LA Membrane - -

Pure 1050 850

MDF Standard 1150 900

FR-MDF-LA Firax Class 0 1050 850

Firax 1050 850

MDF-HLS Umidax 1260 1180

Umidax Noir 1250 1180

L-MDF Fibrabel 875 700

Pure Light - -

L-MDF-FR Firax LIght 875 700

L-MDF-H Umidax Light 900 790

UL2-MDF MDF Ultra Light 550 400

MXL 375 0

MDF class Spanolux MDF Tensile strength perpendicular to surface (N/mm) EN 319

(average values)

MDF-LA Membrane -

Pure 0,74

MDF Standard 0,64

FR-MDF-LA Firax Class 0 0,41

Firax 0,55

MDF-HLS Umidax 0,83

Umidax Noir 0,83

L-MDF Fibrabel 0,50

Pure Light 0,46

L-MDF-FR Firax LIght 0,41

L-MDF-H Umidax Light 0,57

UL2-MDF MDF Ultra Light 0,33

MXL -

resistance to delamination or splitting on the face. As a rule, the thicker the panel, the lower the normal tensile strength. Table 9 shows the normal tensile strength values for the different MDF types, for a panel of 18mm thickness.

Table 10: Screw withdrawal resistance as per standard EN 320

3.8. Formaldehyde emission

In the production of Spanolux MDF boards, resin types (UF and UMF) are used that may release formaldehyde. Since high concentrations of formaldehyde in buildings may cause irritation of eyes and upper respiratory tract, requirements are imposed on the emission values of MDF.

The emission of formaldehyde decreases in time (after manufacture) but increases at high humidity and temperature. It can be greatly inhibited by finishing the board with a film-forming product (paint, varnish) or by coating the board with e.g. a synthetic finish or melamine.

For the emission of formaldehyde of uncoated or unfinished MDF, the formaldehyde content is determined in accordance with:

The perforator method as per standard EN 120 The chamber method as per standard EN 717-1 The bottle method as per EN 717-3

For MDF, standard EN 622-1 defines the following two classes for the content of free formaldehyde and formaldehyde emission.

Table 11: Requirements for formaldehyde content (g) and formaldehyde emission (e) of MDF. All MDF boards from the Spanolux range belong to the lowest formaldehyde class, E1.

Moreover, Spanolux has the Pure and Pure Light MDF boards, which have extremely low formaldehyde

Klasse Formaldehydegehalte EN 120

Formaldehyde - emissie EN 317-1

mg / 100 g MDF mg / m lucht

E1 g < 8 e < 0,124

E2 8 < g < 30 e > 0,124

emission comparable to that of natural wood. Natural wood has perforator values < 2 mg/100g dry matter. Pure and Pure Light achieve the same low formaldehyde emission values. These boards are made of 100% spruce and eminently suitable for interior design applications where attention is focused on the use of ecological products.

Pure and Pure Light are intended for use in general housing construction, in areas with low ventilation, high humidity and/or ambient temperature, and in buildings such as schools, hospitals and museums.

3.9. Thickness swelling 24 hours

Depending on the use and the resin used, two types of MDF boards can be distinguished: MDF boards for use in a dry environment:

Membrane, Pure, MDF Standard, Firax Class 0, Firax, Fibrabel, Pure Light, Firax Light, MDF Ultra Light and MXL.

A dry environment is defined as a normal indoor climate (as e.g. in living rooms and bedrooms) corresponding to use class 1, as specified in ENV 1995-1-1 (temperature 20 + 2C; relative humidity > 65% for a few weeks per year only), and with biological risk class 1 as per standard EN 335-3.

MDF boards for use in a humid environment:

Moisture resistant MDF: Umidax, Umidax Noir or Umidax Light

A humid environment is defined as a temporarily humid indoor climate (as e.g. in kitchens, bathrooms, unheated garages and unheated washrooms) corresponding to use class 2, as specified in ENV 1995-1-1 (temperature 20 + 2C; relative humidity max. 85% for a few weeks per year only), and with biological risk class 1 as per standard EN 335-3.Test method EN 317 determines the percentage of thickness swelling of the central point on test specimens of 50 x 50 mm after immersion in cold water (20C) for 24 hours. These values classify the different MDF types in terms of behaviour upon wetting. Values for swelling of the edge areas and long term swelling are not determined on the basis of EN 317.

Table 12 indicates the thickness swelling, determined as per EN 317, of the different types of Spanolux MDF for three board thicknesses: 12mm, 18mm and 25mm.

Load duration class kmod kdef

Service class Service class

1 2 1 2

Permanent 0,20 - 3,00 -

Long-term 0,40 - 2,00 -

Medium-term 0,60 - 1,00 -

Short-term 0,80 - 0,35 -

Instantaneous 1,10 - / /

Table 9: Tensile strength perpendicular to surface as per standard EN 319, for panels of 18mm thickness.

3.7. Screw withdrawal resistance

MDF has a significantly higher resistance to screw withdrawal as compared to other board materials. Table 10 indicates the screw withdrawal resistance for a steel screw with 4.2mm diameter and 38mm length with 15mm screwing depth, determined in accordance with EN 320, for different Spanolux MDF types of 18mm thickness.

Table 12: Thickness swelling as per EN 317

3.10. Durability

3.10.1. Cyclic test

The durability or the behaviour of MDF under extremely humid conditions can be assessed by two test methods.

The durability of MDF for applications under humid conditions can be determined by determining the tensile strength perpendicular to surface and the thickness swelling after a cyclic test in accordance with EN 321. In this cyclic test or Option 1, the MDF test specimen is subjected to 3 successive cycles of the following exposure treatments: immersion in water, frost and heat. Upon completion of the three cycles, the tensile strength perpendicular to surface and the thickness swelling of the MDF test specimen are determined. This cyclic test is also known as the V313 test. The name is derived from the cycle which is repeated three times (with 4-hour intervals for reconditioning of the MDF test specimens), each cycle consisting of:

3 days: immersion in water at 20C (with subsequent removal from the water)

1 day: freezing at a temperature of -20C 3 days: drying at a temperature of 70C (see figures

7 through 9)

Table 13: durability of moisture resistant Spanolux MDF (Umidax , Umidax Noir and Umidax Light) of 18mm thickness after the cyclic test (Option 1).

17

3

16

MDF class Spanolux MDF Option 1

Tensile strength perpendicular to surface (N/mm)

EN 321(average values)

Thickness swel-ling (%)EN 321

(average values)

MDF-HLS Umidax 0,35 5

Umidax Noir 0,35 5

L-MDF-H Umidax Light 0,25 - 0,30 8

Figure 7: V313/Option 1: 3 days immersion in water at 20C.

Figure 8: V313/Option 1: 1 day freezing at a temperature of -20C

Figure 9: V313/Option 1: 3 days freezing at a temperature of 70C

3.10.2. Boiling test

An alternative method for testing the durability of MDF is to determine the tensile strength perpendicular to surface after the so-called boiling test in accordance with EN 1087-1. In this boiling test or Option 2, the MDF test specimens are immersed in boiling water for two hours. The MDF test specimens are subsequently cooled and then the normal tensile strength is determined. (see Figure 10)

Figure 10: Set-up used to determine the normal tensile strength.

Country Test method Firax Thick-ness(mm)

Firax Class

0

Thick-ness(mm)

Firax Light

Thick-ness(mm)

Belgi S1-203 A1 6-25 A1 10-25

Europa EN 13501-1 B-s3, d0

6-25 B-s3, d0

12-25

Frankrijk NF P 92.507 M1 6-25 M1 12-18

Duitsland DIN 4102-1

Itali CSE RF 2/75/A CSE RF 3/77

1 10-18 1

Neder-land

NEN 6065 NEN 6066

Spanje UNE 23.727-90 M1 12-30 Class 1

10-25

Engeland BS476-7 Class 1

6-30

Engeland BS476-7 BS476-6

Class 0

12-18

USA ASTM E84 A 12-25

3.11. Surface strength

The surface strength is determined in accordance with standard EN 311. The purpose here is to determine the force that is required to remove the surface layer of a wood board material in a perpendicular direction. This property is particularly important for surface finishes such as melamine, HPL, laminate, etc.

3.12. Fire behaviour

Specifications for structural applications often include requirements for limiting flame spread along the surface of a board material, burnthrough time or flashover. In this respect, Standard MDF has properties that are similar to those of solid spruce, with special coatings that act as flame-spread retardants.

For more rigorous fire requirements, a fire retardant MDF panel to which fire retardants are added during the production process, can be used. Fire retardant MDF, with the fire retardant homogeneously distributed in the mass, is to be preferred to MDF that is impregnated afterwards. Spanolux has many years experience in the production of fire retardant MDF.

MDF with weight by volume 600 kg/m and thickness 9 mm has fire class D-s2,d0 or DFL-s1 (for flooring). These fire classes do not apply to UL2-MDF (MDF Ultra Light and MXL).Spanolux has special certificates for MDF Standard 6mm and Fibrabel 8mm that prove that also these thin panels meet the needs of D-s2,d0.

The addition of fire retardants allows MDF to be classified into a higher fire class. Spanolux has a wide range of fire retardant MDF boards with Firax, Firax Class 0 and Firax Light. These MDF boards have vastly improved heat and fire resistance, enabling their use in public buildings such as hospitals, airports, rest homes, theatres, hotels, museums, etc. The burnthrough time is 30 mm/hour or 0.5 mm/min. Spanolux fire retardant products are backed up by national and international test reports (see Table 14).

Density Thermal con-duction coef-

ficient

Vapour diffusion re-sistance number

Sound absorption coefficient

(kg/m) (W/mK) (wet) (dry) 250 tot 500 HZ

1000 tot 2000 Hz

400 0,07 5 10 0,10 0,20

600 0,1 12 20 0,10 0,20

Table 14: Overview of national and international test reports for Spanolux fire retardant products.

MDF class Spanolux MDF Thickness swelling (%)EN 317

(average values)

12 mm 18 mm 25 mm

MDF-LA Membrane - - -

Pure - - -

MDF Standard 10,3 8,5 6,7

FR-MDF-LA Firax Class 0 8,9 6,3 -

Firax 8,0 5,8 7,4

MDF-HLS Umidax 5,6 3,7 3,0

Umidax Noir 5,6 3,7 3,0

L-MDF Fibrabel 11,2 10,1 7,1

Pure Light - - -

L-MDF-FR Firax LIght 9,6 7,1 7,2

L-MDF-H Umidax Light 7,0 4,7 -

UL2-MDF MDF Ultra Light 12,4 11,2 8,9

MXL - - -

3.13. Building physical properties The building physical properties of MDF are determined mainly by the weight by volume.

Table 15: Building physical properties of MDF, determined by the weight by volume.

Different values may be obtained according to the type of MDF, e.g. the vapour diffusion resistance number (wet) for Umidax Light (= 600 kg/m) is 17.

19

4

4.1. Transport and storage

The MDF production method used, in which the fibres are distributed uniformly over the total board thickness, ensures a balanced build-up and permanent flatness of the boards. To preserve this flatness, correct transport and storage is required during the various processing phases.

MDF panels can become permanently deformed in case of improper handling or stacking, e.g. when not supported by flat pallets or a sufficient number of supporting blocks.

The following method is recommended:

MDF panels are best stacked horizontally in packs, preferably on pallets or on dry stacked beams (70 x 70 mm or 90 x 90 mm). On potentially damp substrates, a waterproof foil, e.g. polyethylene foil, is installed before the panels are stacked on it.

When using stacked beams, they must be of equal thickness and spaced no more than 800mm apart. For MDF less than 15mm thick, it is recommended to use stacked beams, e.g. spaced at intervals of 50 times the board thickness (see Table 16). The sides of the panels shall project no more than 200mm from the outer stacked beams.

18

4. General guidelines for the use of MDF

Panel thickness (mm)

Spacing between beams (m)

Panel length (mm)

Min. number of beams per pallet

6 0,3 2500 8

8 0,4 2500 6

10 0,5 2500 5

12 0,6 2500 4

Table 16: Minimum number of stacked beams in relation to panel thickness

The stacked beams are placed on top of each other, in order to prevent deflection of the MDF.

Vertical stacking of a small number of panels is acceptable, provided the panels are properly supported and stacked vertically (or almost vertically).

Figure 12: Vertical stacking

The storage area must be dry and well ventilated. An average relative humidity of 50% ensures a moisture content of 7 to 9% in the panels.

Where extremely damp or extremely dry conditions may occur during transport, temporary storage or on site, the panels are wrapped in plastic foil.

To limit the adverse effects of varying ambient conditions, one or two scrap panels are placed on top of the stacks during processing or for prolonged storage periods.

Figure 11: Minimum number of stacked beams in relation to panel thickness

The edges of stacked panels are aligned to prevent damage caused by bumping against overhanging edges or corners and discoloration due to sunlight.

Figure 13: Storage of MDF packs

4.2. Moisture content in MDF

After production, MDF has a moisture content of 8 3%. At the time of delivery to the end-user, however, the moisture content may have altered due to ambient factors during transport and storage. In particular, storing the panels in a humid environment on the construction site will inevitably lead to water absorption (albeit to a limited degree); conversely, the moisture content will decrease in a very dry environment. Such moisture content variations initially occur at the edges of the panels and in the outer panels of a stack, but can subsequently spread to all panels of the stack.

Dimensional variations can to some extent be limited by treating and processing MDF at a moisture content that approximates, as closely as possible, the expected equilibrium moisture content. This equilibrium moisture content is dependent on the climate (and the season) and on the conditions in which the material is processed.

21

5

For the processing of MDF, it is recommended to take into account possible dimensional variations that may be caused by alteration of the equilibrium moisture content in the MDF. Dimensional stability of MDF can be obtained by treating and processing MDF at a moisture content that approximates, as closely as possible, the expected equilibrium moisture content. This equilibrium moisture content is mainly dependent upon the relative humidity and temperature of the environment in which the material is processed.

5.1. Sawing

MDF can be sawn both manually and by machine, without causing the material to splinter or fibres to be torn out of the panel. For manual sawing of MDF, a fine-toothed saw is recommended, whereas for mechanical sawing, the saw blades normally used for particleboard can be used.

On the other hand, the high density of certain MDF panels, in combination with the use of resin as binder, means that MDF will cause the tools to wear slightly more rapidly as compared to the sawing of solid wood. Whereas HSS (High Speed Steel) cutting tools are used for conventional mechanical woodworking, the use of hard metal (HM) or Widia tools is recommended for the processing of MDF.

For the processing of large MDF quantities, the use of polycrystalline diamond (PCD) saw teeth may, in spite of the higher cost, be economically justified because of their longer working time (i.e. the time between regrinding of the tool).

For intricate shapes and patterns, high-energy laser beams can be used, provided that charred fragments (fire stains) are admissible or can be removed by sanding.

Based on research and experience, a number of general recommendations can be made both to obtain smooth surfaces and sawn edges, and to lengthen the lifetime of the tools.

20

5. Processing

5.1.1. Rotation Speed

A correctly set speed ensures optimal operation and working time of the tool. The maximum speed indicated on each saw blade should in no case be exceeded..

5.1.2. Cutting speed

The cutting speed (Vc) is the distance travelled by the point of a cutting edge with the greatest cutting circle diameter, expressed in m/s. The cutting speed can be calculated with the following formula:

Vc = ( d * 3,14 * n ) / (1000 * 60)

Vc = cutting speed (m/s) d = diameter of saw (mm) n = speed (number of revolutions per min.) (r.p.m.)

For MDF, a circumferential speed of 60 to 70 m/s is recommended.

Table 17 below gives an overview of the sawing speeds for a number of saw blade diameters and a number of speeds.

5.1.3. Feed rate

When sawing MDF, the panel material must be passed across the saw blade at a high enough feed rate.

At too low a feed rate, the saw blade teeth will not cut, but instead crush and rub down on the panel material, whereby burning may occur and fine dust is generated. The friction heat, which is generated by the pressure on the teeth, may significantly reduce the lifetime of the saw (working time).

Saw blade diameter

(mm)

Speed (r.p.m.)Panel length (mm)

500 1000 1500 3000 4000 5000 6000 8000 10000 12000

100 3 5 8 16 21 26 31 42 52 63

150 4 8 12 24 31 39 47 63 79 94

200 5 10 16 31 42 52 63 84 105

250 7 13 20 39 52 65 79 105

300 8 16 24 47 63 79 94

350 9 18 27 55 73 92 110

400 10 21 31 63 84 105

450 12 24 35 71 94

500 13 26 39 79 105

Table 17: Cutting speed (m/s) versus speed (r.p.m.)

At too high a feed rate, the sawn edges will be of poorer quality, as evidenced by a fraying saw cut.

It is recommended that the chip thickness, or the amount of material that is removed by each saw blade tooth, vary between 0.15 and 0.25mm. (For HDF, this value varies between 0.05 and 0.12 mm). To achieve this feed per tooth, the feed rate can be calculated as follows:

vf = fv * z * n

vf = feed rate (m/min.) fv = feed per tooth z = number of teeth n = speed (r.p.m.)

Example: When using a 40-tooth saw blade and a speed of 3000 r.p.m., the plate feed rate must be comprised between 18 m/min. (chip thickness, or feed per tooth, 0.15mm) and 30 m/min. (chip thickness, or feed per tooth, 0.25 mm).

5.1.4. Geometry of the saw teeth

The shape, position and dimensions of the saw teeth are essential technical characteristics to obtain a good end result.

It is recommended to slightly increase the normally used clearance angle, to allow efficient removal of the fine dust generated during the processing of MDF. In addition, a larger clearance angle will prevent the deposition of resins on the tooth points.

Experiments have shown that the following shape, position and dimensions of saw teeth produce good results:

Top angle 15 (alternating per tooth in both directions)

Lateral clearance angle 2 4 Clearance angle 20 22 Rake angle 15 Clearance between 0,25 0,45 mm tip and tooth

The height setting of the saw blade (or saw blade overhang) is in principle sufficient when the saw teeth project just above the panel. In this way, a maximum

length for the saw cut is achieved. A higher setting will produce a poorer cut at the bottom of the panel.

During sawing, the MDF panel should be kept perfectly level and the saw blade must be free of vibrations.

MDF can also be finished with a layer of veneer, a layer of melamine, or a melamine-faced synthetic panel (HPL = High Pressure Laminate). For sawing this type of panels, a saw blade with an axis angle of 5 and a top angle of 15 is recommended (both alternating: Alternating per tooth in both directions). Chipping can be prevented through the use of a scoring saw on the bottom side.

5.1.5. Tool maintenance

Proper maintenance of the sawing tools used is also of great importance in ensuring constant and good sawing quality.

During grinding, all original angles of the saw teeth must be maintained. Smaller angles will give rise to resin deposits on the saw teeth, whereas larger angles will reduce the working time. The tooth base must be cleaned at regular intervals to ensure efficient dust collection. Resin deposits can be reduced by polishing the teeth after grinding.

Figure 15: Mitre sawing of MDF

Figure 14: Saw-tooth shape and dimensions

FRONT VIEW TOP VIEW SIDE VIEWNotch

Top angle

Tip

Tooth Radial clearance angle

Clearance between tip and tooth

Lateral clearance angle

Tip

Tooth

Tooth base

Axis angle

Clearance angle

Tooth

Tip

Wedge angleRake angle

Tooth base

23

5

22

5.2. Drilling

For drilling MDF panels, standard drills and speeds of approx. 3500 r.p.m. are recommended, which allows high quality drilled holes with limited material accumulation on the rear side to be obtained.

To prevent material tearing on the rear side in case of drilled through holes, it is recommended to drill half of the hole depth on either side of the panel. Special care should be take to drill both hole halves in a perfectly straight line.

Figure 17: Minimum curvature radius of the edges

FOUT CORRECT

kitchen doors), a minimum radius of 3mm is recommended. Where no such risk exists, the edges can simply be broken in order to obtain a good paint or varnish covering.

Fine machining: fz = 0.3 mm Average machining: fz = 0,8 mm

Number of cutting edges z

Speed (r.p.m.) Speed (r.p.m.)

3000 4500 6000 9000 12000 15000 18000 3000 4500 6000 9000 12000 15000 18000

1 1 1 2 3 4 5 5 2 4 5 7 10 12 14

2 2 3 4 5 7 9 11 5 7 10 14 19 24 29

3 3 4 5 8 11 14 16 7 11 14 22 29 36 43

4 4 5 7 11 14 18 22 10 14 19 29 38 48 58

6 5 8 11 16 22 27 32 14 22 29 43 58 72 86

Table 18: Feed rate vf (m/min.) for fine machining, with feed per cutting tooth = 0.3 mm, and for average machining, with feed per cutting tooth = 0.8 mm.

The feed rate also depends on the number of cutters, the speed and the feed per cutting tooth. The maximum speed indicated on the tool should in no case be exceeded. The number of cutting edges can be calculated as follows:

z = (vf * 1000) / (n * fz)

vf = feed rate (m/min.) n = speed (r.p.m.) z = number of cutting edges fz = feed per cutting tooth (mm)

Table 18 contains a number of feed rate reference values for fixed parameters of feed per cutting tooth. Fine machining denotes reference values for a 0.3 mm feed per cutting tooth, and average machining those for a 0.8 mm feed per cutting tooth.

In all cases, reference values are used, the aim being, where possible, to achieve the highest possible feed rate (limited as a function of the above-mentioned parameters).

At a lower speed, the cutting edges will compress and grind down the edges of the MDF, and the resultant friction heat will reduce the working time of the cutting edges.

Profiles for which a large amount of material has to be removed or that have deep cuts, may require pretreatment such as rough milling. After rough milling, the final shape is milled and a smooth surface is obtained (e.g. with fine machining).

When working with an already-coated MDF (e.g. with melamine), different reference values apply. As a rule, coated MDF panels require a lower feed rate than uncoated MDF panels, depending on the type of material with which the MDF is coated.

5.3.3. Geometry of the cutters

To find the correct balance between the working time of the tools and the quality of the profiles, the tool must be set at the correct angle to the MDF.

The choice of angle for the cutters used to profile or mill MDF is determined by balancing the working time of the tool and the quality of the cut edge. A large rake angle is necessary to obtain a smooth cut edge with minimum wear of the tip. A wide clearance angle prevents the back of the cutter from rubbing against the already-processed material. However, these two angles cannot be increased indefinitely because a sufficient metal thickness must remain present at the tips.

Figure 16: Drilling in MDF

5.3.1. Cutting speed

The cutting speed (Vc), expressed in m/s, is determined by the diameter and speed of the cutting tool. The cutting speed is calculated according to the following formula:

Vc = ( d * 3,14 * n ) / (1000 * 60)

Vc = cutting speed (m/s) d = diameter (mm) n = speed (number of revolutions per minute) (r.p.m.)

For profiling or milling of MDF, a cutting speed of 60 to 80 m/s is recommended.

5.3.2. Feed rate

The feed rate for milling or profiling operations initially depends on a number of parameters: Desired finish, which in turn depends on the desired

result in the end application.

Strength of the cutter: The rule of thumb here is that the maximum feed rate is limited by the value: vf < d /2

vf = feed rate (m/min) d = diameter (mm) Example: for a cutter with 4mm diameter, a maximum feed rate of 2 m/min can be used without any risk of the cutter being broken.

Capacity of the milling machine motor.

Stability of the set-up and the machine.

Figure 18: CNC surface milling in MDF

5.3. Profiling (Milling)

Almost any MDF profile can be profiled or milled. In addition, a highly polished edge finish can be obtained, allowing grinding and application of a pore filler to be reduced to a minimum.

For rigid and sharp profiles, it is advised to use hard metal (HM) tools. For large series, the use of polycrystalline diamond (PCD) cutting tools is recommended, as it allows a working time to be achieved that is 30 to 50 times that of conventional hard metal tools.

Simple profiles with curved edges are to be preferred to sharp edges. Simple profiles have the advantage of being easy to grind and require less preparation for the final finish. The slightly radiused edges are better coated with paint or varnish and will therefore offer greater resistance to hard impacts.

Where there is a risk of damage by impacts (e.g.

25

5

24

Cutters for the processing of MDF are normally provided with angles in the order of:

rake angle (a) 10-20 clearance angle (b) 20-22

To reduce the impact of the cutters on the edges of the MDF panel, the rake angle can be set to approx. 10, so as to obtain a progressive cutting of the panel.

The time for regrinding can be determined by regularly checking the profiled edges or by measuring the current consumption of the milling machine (regrinding can be envisaged when the initial current consumption has increased by e.g. 10%).

5.3.5. Clamping the workpiece

For profiling or milling it is important that the workpiece is properly clamped, so that the vibrations caused during milling are not transmitted to the workpiece. When clamping the workpiece, it is also important to correctly position the workpiece and to make sure that this position is maintained throughout the milling.

On a CNC milling machine, vacuum suction cups are generally used to clamp the workpiece. For lighter MDF types such as MDF Ultra Light and MXL, special attention must be paid to the clamping of the workpiece to ensure that the vacuum suction cups will not partially suck air through the panel.

5.4. Laser cutting

MDF laser cutting is a new, effective technique, which, unlike conventional techniques, enables small thicknesses to be cut with high precision and quality.

In addition, in contrast to the customary mechanical tools, the laser works contact-free, making it virtually wear-proof. The benefits of laser cutting are:

High cutting speed High efficiency minimum loss of material Ideal for production prototypes Allows cutting in small, medium sized and large quantities

Due to the thermal laser process, the laser cut edges of the MDF will carbonise or blacken. The thicker the MDF panel, the more pronounced this phenomenon becomes.

5.5. Sanding

The quality of the finish greatly depends on the preparation of the surface, mainly at the level of the edges.

At the end of the production process, the top and bottom side of the MDF panels is first calibrated with grit 60 or 80, followed by fine sanding over the sanding base with grit 100 and 150. The surface that is thus obtained is suitable for most finishes such as veneer gluing or pressing with plastic film. To obtain a high quality lacquer finish, it is advisable to re-sand the MDF with grit 180 (or higher). For very high quality requirements (e.g. high gloss lacquer), it is recommended to re-sand the surface using an even finer grit (> 200).

For fine sanding, silicon carbide sanding belts are advised. Aluminium oxide sanding belts tend to become dull more rapidly, reducing their effectiveness.

Profiled edges or milled recesses can also be fine sanded. The higher the quality of the operation - sawing or milling - the less re-sanding will be required (depending on the desired end result). Sanding of profiled edges is important to obtain a smooth and perfect final finish. When sanding with grit between 150 and 240, the upright fibres and irregularities created during milling, are removed to prevent pilling and marking of the fibres when e.g. a first lacquer coat is applied. 5.5.1. Sanding methods

Obviously, less sanding will be required after mechanical processing than after manual processing.

The choice of sanding method for subsequent finishing depends upon the complexity of the profiles, the number of different shapes, and financial considerations.

Manual sanding:

In manual sanding, a flexible sanding block with the form of the profile as support for the sandpaper, can be used to prevent excessive radiusing of sharp edges and the flattening of bent sections in the profile. For sanding edges, grit 150 to 240 is recommended.

Sanding discs:

Sanding discs are used for sanding edges with more complex profiles and for sanding internal profiles. These discs are adapted to suit the form of the profile. Here, the optimal grit size varies from 60 to 100.

Sanding discs can be used both on manual machines and on machines with automatic feed.

Figure 19: Angles of the cutters: (a) rake angle, (b) clearance angle

Surface milling cutters are employed for use on CNC-controlled machines. These tools and machines are ideally suited for manufacturing the most intricate, both two- and three-dimensional, shapes in MDF.

Surface milling cutters are generally characterised by a:

Rake angle 15-25 Clearance angle 15-18

5.3.4. Tools

The use of hard metal cutters is recommended because they produce a better surface finish and have a longer working time.

Disposable cutters have better technical performance but the material is more brittle. The use of disposable cutters is cost-effective because of the limited downtime of the machines, the correct profiling, and the constant diameter of the cutter (no adjustment necessary). The cutter can either be turned around or replaced, whilst the tool itself remains on the machine.

For series production, increasing use is being made of polycrystalline diamond milling tools. The high purchase price is offset by the on average longer working time. Automatic feed is recommended for economic reasons.

To obtain a true cut edge, without any fibres being burnt or torn loose, and to lengthen the lifetime of the tools, the milling tools is reground at regular intervals. During regrinding, the rake angles and clearance angles must be maintained.

Figure 20: MDF laser cutting

Figure 21: Laser cut MDF

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Sanding belts:

Sanding belts can be used for simple profile shapes. A fine finish is obtained by sanding in two steps: first with grit 80 against the feed direction and then with grit 120 in the feed direction.

The panel surface can also be fine sanded using sanding belts with grit size less than 150, e.g. for lacquering MDF surfaces.

Sanding belts have the advantage that they last longer because a lower temperature is generated by the associated friction. Sanding belts are less suited for intricate profiles.

Sanding brushes:

Sanding brushes can be mounted both on manual machines and on a sanding facility of a production line. They are efficient for deep and narrow profiles or for very wide milled recesses (several layers of brushes on top of each other). The recommended speed can amount up to 3000 r.p.m., depending on the brush diameter.

Profiled sanding heads:

For sanding intricate profiles, profiled sanding heads are advised. Here, the head is first formed (mirror image of the profile to be sanded) and then enveloped with elastic sandpaper. For more complex profiles, a series of wheels can be mounted behind or above each other.

Systems are also being developed in which 6, 8 or 10 rubber blocks are attached to the circumference of a sanding head. The profile shape is sanded in the rubber blocks, and then the sandpaper is attached to the created profile.

5.5.2. Sanding dust

The sanding dust generated during the processing and machining of MDF is finer than that of solid wood or particleboard. The dust collector on a woodworking machine must have sufficiently high air velocities, notably at least 20 to 30 m/s at the exhaust hood and 15 to 20 m/s in the main pipe. The velocity in the main pipe is relevant to avoid dust accumulation. Moreover, the exhaust hood must be located as close as possible to the workpiece. If a central exhaust system is used, it is recommended not to shut off unused openings.

Because of the risk of explosion and ignition, it is recommended to install spark detectors and an automatic fire extinguishing system in the exhaust installation. This recommendation does not apply to exhaust installations that process less than 20 percent by volume of MDF dust.

Figure 22: Sanding head for MDF edges with special shapes

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Fasteners that can be used in or with MDF include screws, nails, rivets and glues. Various joints such as end, butt, angle, dowel and removable joints or the use of fittings can be applied.

6.1. Screws MDF offers excellent resistance to screw pull-out (screw-holding capacity), both in the face and on the edges. Most types of screws can be used. Cylindrical, straight shaft screws with the greatest possible ratio of total screw thickness to shaft thickness, are recommended.

6. Fasteners and joints

A small chamfer at the end is desirable to prevent lift-up around the screw head. In some cases, the use of screws having a part with no screw thread is recommended.

Predrilling is always required for inserting screws into MDF, and into the edges in particular. The hole to be predrilled must be larger than that used for solid wood or particleboard. As a general rule, it is recommended to drill a hole with a diameter that is slightly smaller than the shaft diameter (see table 19) and at least 1mm deeper than the total screw length. This is especially important when screwing into the edges of thin panels.

Figure 23: Screw connection in MDF

Figure 24: Screws in MDF

Table 19 below shows the drilled hole diameter (rounded to 0.5 mm) relative to the screw diameter.

(mm) Screw (mm) Shaft (mm) Drilled hole

3,0 2,2 2,0

3,5 2,6 2,5

4,0 3,1 3,0

4,5 3,6 3,5

5,0 4,2 4,0

Table 19: Drilled hole diameter (rounded to 0.5 mm) in MDF relative to the screw diameter..

The minimum spacing between the screws and the workpiece edges depends on the panel thickness. For screwing into the edges, a distance of 70mm to the corner is recommended. min. 70mm to the corner/edge

Figure 25: Minimum distance to workpiece edge when screwing

For screwing large size panels (e.g. walls), a minimum distance of 12mm to the panel edges and 25mm to the corners should be preferably be observed (see also Figure 26). Resistance to screw pull-out is great compared with other types of wood-based panels.

Figure 26: Minimum distances to the edges when screwing large MDF panels.

Table 20 below shows the values for screw pull-out resistance as per EN 320 in the face and in the edge for the different types of Spanolux MDF, for a panel thickness of 18 mm. Even in the lighter density MDF types, such as MDF Ultra Light, fittings can be applied using standard screws. For MXL, the use of standard screws in combination with furniture fittings is not recommended. This MDF type did not pass the tests.

MDF - class Spanolux MDF Screw pull-out resistance (N)EN 320

(average values)

Face Edge

MDF-LA Membrane - -

Pure 1050 850

MDF Standard 1150 900

FR-MDF-LA Firax Class 0 1050 850

Firax 1050 850

MDF-HLS Umidax 1260 1180

Umidax Noir 1282 1180

L-MDF Fibrabel 875 700

Pure Light - -

L-MDF-FR Firax LIght 875 700

L-MDF-H Umidax Light 900 790

UL2-MDF MDF Ultra Light 550 400

MXL 375 0

Table 20: Screw pull-out resistance as per EN 320 in the face and in the edge for different types of Spanolux MDF, for a panel thickness of 18 mm.

A higher screw pull-out resistance in the edge of the panel can be obtained by gluing together two panels of the same MDF type and then driving screws into the glued joint. Processing of light MDF panels where screwing into the edges is required can be done in this way, which at the same time allows higher thicknesses to be achieved.

Table 21 below shows that glued panels can achieve screw pull-out resistance values that are twice to three times as high.

MDF class Spanolux MDF Screw pull-out resistance (N) as per EN 320

on glued joint

MDF-LA MDF Standard:2 x thickness 38 mm glued

1840

L-MDF Fibrabel: 2 x thickness 38 mm glued

1980

UL2-MDF MDF Ultra Light: 2 x thickness 38 mm glued

1120

Table 21: Screw pull-out resistance on the glued joint of composite panels.

It should be noted that predrilling is not required when using certain special MDF screws, enabling a significant saving in processing time. These screws drill themselves into the MDF panel without causing the MDF to split or deform. These special screws could also be used closer to the edge and should also be more easy to use in the end edges, making them suitable for MDF angle joints (e.g. Spax-M from ABC Verbindungstechnik, and the pfs-screw: type M from PGB-Fasteners. (see Figures 27 and 28)

Screws can be neatly concealed using putty (white colour) or MDF filler (brown paste). After the putty has cured, the surface must be fine sanded. (see Figure 29).

Figure 27: Screwing together MDF without predrilling using standard parallel screw: Spax-S.

Figure 29: Finishing method for concealing visible screws.

Figure 28: Screwing together MDF without predrilling using special screw: Spax-M.

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6.2. Nails

With the exception of small diameter nails (needle diameter: small shaft of e.g. 1.2 mm and 40 to 60 mm length), the use of nails is to be avoided. Thin nails in the edges are driven in at 150 mm intervals, preferably with a pneumatic nail gun under a small angle with respect to the panel surface. To prevent splitting, the nails are mounted at least 70 mm away from the corner.

6.3. Rivets

Rivets are mounted with a pneumatic riveting gun, e.g. as a temporary fastener for glue joints in MDF. Rivets can also be used to fasten MDF to a frame or decorative frames to the edges of MDF.

Riveting produces a tight fastening in the face of MDF, provided they are placed at least 12 mm away from the edge and 25 mm from the corner. Rivets should not be placed any closer to the edge, except in the case of small loads. A better fastening is obtained in combination with glue. When riveting in the side of MDF, the distance to the corner should be at least 70mm, with the rivets being driven in under an angle of 15 to 30 with respect to the face in order to obtain a better fastening and to prevent splitting.

6.4. Gluing

Gluing MDF normally does not present any particular problems. The choice of glue depends on the properties of the materials to be glued.

Temperature and ambient humidity during application and curing of the glue are essential to obtain good results. A minimum temperature of 15C is recommended for the processing of most glues. Also the moisture content and the temperature of the panels and the planned surface finishes (e.g. veneering) must comply with the instructions of the glue manufacturer and approximate as closely as possible the eventual equilibrium moisture content of the woodwork after installation. Furthermore, the absorption power of the panel and the differences in absorption between the various parts of a single panel (face / edges) must be taken into consideration.

Other factors influencing the choice of glue include the glue application method (by hand, roller or spray gun), flammability, press parameters, etc.

The surfaces to be glued should be as large as possible for maximum load transmission capability. Any forces acting on the joint should be distributed as much as possible across the entire glued joint.

There are a number of suitable glue joints, which are represented in Figure 30.

Most wood glues are also suitable for gluing MDF. When gluing non-MDF to MDF, the choice of glue is usually determined by the surface of those materials.

Figure 32: Glued MDF panels: 2 x 38 mm MXL.

Gluing of different types of Spa-nolux MDF

MD

F-L

A

FR

-MD

F-L

A

MD

F-H

LS

L-M

DF

L-M

DF-F

R

L-M

DF-H

UL2-M

DF

Mem

bran

e

Pure

MD

F Sta

ndar

d

Fira

x Cla

ss 0

Fira

x

Um

idax